old motor

[Larry Blanchard]

Some of you will remember that I acquired an old (1948) Delta/Rockwell table saw and am restoring it. Well, I've got the saw pretty much done except for derusting the top. Everything else has been cleaned and repainted and the arbor has new sealed bearings.

So now I'm looking at the motor and scratching my head. The previous owner put a 20' cord on it using what appears to be 8 gage wire. He wired it to a 3 prong plug and I would have assumed it was grounded had I not opened it up and found only two wires :-).

But it's the wiring diagram that really puzzles me. The motor will, according to the label, run either CW or CCW on either 110 or 220. But the wiring diagram on the outside of the wire box does not differentiate between 110 or 220. It just shows:

CW:

1 & 4 - line 1 3 & 2 - Line 2

CCW:

1 & 2 - line 1 3 & 4 - line 2

Someone has x'd out the diagram with a metal stamp. When I open the wiring box, there is a handwritten diagram with the following:

For 110: CW:

5 & 2 & 3 - line 1 6 & 4 & 1 - line 2

CCW:

5 & 4 & 3 - line 1 6 & 2 & 1 - line 2

For 220: CW:

5 & 2 & 6 - jumpered 3 - line 1 4 & 1 - line 2

CCW:

5 & 2 & 6 - jumpered 4 & 3 - line 1 1 - line 2

And yes, there are 6 wires inside. It is currently wired for 110 CW and I'll keep it that way. But I want to add a ground wire and reduce the wire gage and cord length to something more reasonable. Say 6' and 12 gage wire.

Can I just attach a ground wire to a cleaned screw on the case?

Can anyone explain those wiring diagrams to me?

Since this is AC, I assume it makes no difference which wire is line 1 and which is line 2 - is that correct?

Finally, if it helps, here's what else I know about the motor:

Westinghouse Life Line, style 1456101 capacitor start induction run

203 frame, 6.6 or 13.2 amps, 1 horsepower, 1740 rpm

And it weighs a ton!

All help appreciated - I did a Google but didn't find anything specific on this motor. Only references to Westinghouse Life Line motors were like 50 horse, 300 horse, etc..

[clare]

Fasteneng the ground to a case screw is the right way to do it. The heavy guage cord is REQUIRED if you are more than about 10 feet from the plug-in. I have a "35 amp" extention cord that I used to run my old Beaver saw. Using a regular cord itlost a lot of power and spun up slow - but it didn't blow a 15 amp fuse if I got the blade jammed. With the heavy cord I always used a 20 amp fuse ( and I blew a few of them ) - running a 1 HP Century repulsion start motor.

[Dan Coby]

The ground wire is for safety. You want it to be electrically connected to any part to the motor housing which might be touched by the motor operator (i.e. you). Also long as the various parts of the motor are conductive and you can make a good electrical connection to the case and the pieces of the case are all conductive, then yes, that is what I would do for a ground connection. I would also use an ohm meter to verify that there are no electrical connections between any of the motor windings and the case.

There are three 110 windings in the motor. The starting winding is connected between 2 and 4. (This comes from the 110 diagrams. This pair of connections is reversed to change the direction of the motor.) The other two pairs of windings are 1 to 5 and 6 to 3.

For 110 volt operation: All three winding are connected in parallel. The starting winding 2-4 is reversed to change the direction of the motor.

For 220 volt operation: The two running windings (1-5 and 6-3) are connected in series. Thus there will be 110 volts across each winding. The starting winding (2-4) is connected to the mid point of the two running windings. By connecting to the midpoint, there will also be 110 volts across the starting winding. To change the direction of the motor, the 4 side of the starting winding is moved from line 1 to line 2 (this reverses the current through this winding).

[Pat Barber]

I would take the motor to electrical motor shop, and have them replace the bearing and do a general cleaning of the motor. They will also give you the "correct" setting for the wires for the appropriate voltage setting.

You don't want to toast this old motor if possible. They are VERY hard to replace and very expensive. A new motor for a Unisaw is "around" $300....

The Unisaw motor has special mounting brackets and can not be easily replaced...

Pay up for the shop...

For the derusting:

Soak the top several days in WD-40.

Using a straight razor blade scraper, "shave" the rust and other gunk up. Do this step "several" times.

You will be amazed at how well that will remove a LOT of the rust.

Remove what's left with a ROS sander and progressive grits starting at 60 and work your way up. Use a slurry of WD-40 and clean up after each grit.

Larry Blanchard wrote:

[EXT]

Because the label and the interior instructions are different, I could only assume that the motor has been rewound sometime in the past, and at that point they wound it to work on either 120 or 240 volts. To know the correct wire gauge and fusing, you really need to know the operating amps.

[Larry Blanchard]

OK, could be. But would it make sense that someone had rewound a motor from 2 windings to 3? And remember that the nameplate already stated that it would work on either 110 or 220. How the wiring diagram given would have accomplished that is beyond me :-).

I do know it runs fine on a 20 amp 110 circuit.

I'd almost rather believe that Westinghouse stuck the wrong nameplate on the motor.

P.S. Thanks to all who responded. I'm going to replace the cord with a much shorter one rated for 15 amps and see how it goes. If that doesn't work I'll take it in to a motor shop and let them scratch their heads.

[dpb]

Larry Blanchard wrote: ...

Why, pray tell, would you go to such lengths to make it undersized at the possible savings of a few pennies? At least put a 12ga piece of cord stock on the thing so it will have all the "oomph" it needs for whatever you throw at it w/ stock. If you're going to 240V, then, maybe ok, but still "why?" -- what's to gain?

--

[Lew Hodgett]

WHY????

A few $ invested up front can save a big bunch later.

Lew

[Larry Blanchard]

A: I don't need a 20' cord!

B: The 8 or 10 gauge wire the previous owner used (possibly required due to the length of the cord) is as stiff as a board.

C: And most important, the existing cord is 2 wire - no ground.

FWIW, I finished the rewire today and the motor runs fine. Even the centrifugal switch which I wondered about due to age.

A nice new coat of flat black paint is now drying.